fly in the ointment

fly in the ointment  {n. phr.},  {informal}
An unpleasant part of a pleasant thing; something small that spoils your fun.
We had a lot of fun at the beach; the only fly in the ointment was George's cutting his foot on a piece of glass.
Your new job sounds too good to be true — interesting work, high pay, short hours. Isn't there any fly in the ointment?
Categories: foot {informal} {n. phr.}